1. Field of the Invention
The present invention relates to a pet confinement system, and, more particularly to a wireless pet confinement system.
2. Description of the Related Art
Pet confinement systems often include a radio frequency transmitter having a wire loop for transmitting the radio frequency signal. The wire loop antenna roughly defines the boundary in which the animal is to be confined. The animal wears a receiving unit that is attached to its collar. If the animal gets within a predetermined distance of the wire loop antenna, the receiver unit detects the radio frequency signal transmitted from the loop antenna, whereupon a correcting stimulus such as an electrical shock is applied to the animal. A problem is that it is difficult and time consuming to lay the ground loop antenna. If a discontinuity in the wire loop antenna occurs, it is then necessary to locate and repair the discontinuity. Furthermore, once the wire loop antenna is laid into the ground, the boundaries of the animal's confinement area are fixed, and cannot be easily modified.
It is also known to track an article or person by transmitting an ultrasound signal to a receiver unit carried by the article or person. In response to receiving the ultrasound signal, the receiver unit transmits a radio frequency signal back to the transmitter of the ultrasound signal. Since the speed of sound is known, and radio frequency signals travel practically instantaneously at the speed of light, the transmitting unit can calculate how far away from the transmitter the receiving unit is located based upon the time interval between transmitting the ultrasound signal and receiving the radio frequency signal. If that time interval exceeds a predetermined threshold. indicating that the receiving unit is further than a threshold distance away from the transmitting unit, a second radio frequency signal is transmitted from the transmitting unit to the receiving unit. Upon receiving the second radio frequency signal, the receiving unit applies a correcting stimulus to the animal. A problem is that the battery in the receiver unit must be replaced quite often since the receiver unit must transmit a radio frequency signal almost continuously during operation. Another problem is that devices for transmitting and receiving radio frequency signals must be provided on both the transmitter unit and the receiver unit carried by the article or person, thus increasing the complexity and cost of the overall system.
What is needed in the art is an animal confinement system that can be easily set up and relocated if necessary. Moreover, an animal confinement system including a receiver unit with an extended battery life is also needed.